[Determination of multidrug resistance of M. tuberculosis by different methods]

Testing the direct nitrate reductase technique versus the absolute concentration test has indicated that the former may be successfully used for rapid determination of the sensitivity of Mycobacterium tuberculosis (MBT) to isoniazid and rifampicin and it can reduce the time of obtaining a result by 4-5 times in the cases that sputum bacterioscopy yielded a positive result that allows the modified method to be applied. The advantages of the TB-Biochip technique are the time of detection multidrug-resistant MBT (24 hours), a possibility of obtaining these data just when analyzing sputum-isolated MBT DNA, and characterization of the MBT genomic elements that are responsible for drug sensitivity to antituberculous agents, by determining mutations in the examined genes and this all by using one chip. The agreement of results of microbiological and molecular genetic studies study of drug MBT sensitivity was 98%. There were no differences in the results of those using isoniazid. As for rifampicin, there was a difference in two samples (3.8%). Analysis of a combination of mutations forming multidrug resistance indicated that 74.3% of multidrug-resistant MBT isolates had mutations in the codon Ser531 > Lue of the rpoB gene and in the codon Ser315 > Thr of the katG gene. 97.4% of strains with signs of multidrug resistance had mutations in the codon 315 of the katG gene. 20.5% of isoniazid-resistant strains were observed to have mutations in two genes (katG and inhA) and 28.2% of the strains exhibited double mutation in the katG gene - Ser315Thr and Ile335 > Val.